Tractor fifth-wheel safety lock



Feb-22, 1949. M R 2,462,211

TRACTOR FIFTH-WHEEL SAFETY LOCK Filed Feb. 24, 1947 v 4 Sheets-Sheet l 75 llh E15. 5 7g 3 wm/me CLYDE L. Moo/e5 Feb. 1949. Q MOORE TRACTOR FIFTH-WHEEL SAFETY LOCK 4 Sheets-Sheet 2 Filed Feb. 24, 1947 I I I I I I I I I I I I I I u I n W (I w {1H W m M Pt W KO m m M F 7 INVENTOR. C LYDf L. M0025 Feb 22, 1949. c. L. MOORE 2,462,211

TRACTOR FIFTH-WHEEL SAFETY LOCK Filed Feb. 24, 1947 4 sheets-Susi 3 G 3/ go I W O 534 P1512 33 E U 30 u r CL YDE L. Mooki 0. L. MOORE TRACTOR FIFTH-WHEEL SAFETY LOCK Feb. 22, 1949.

4 Shetgs-Sheet 4 Filed Feb 24, 1947 INVENTOR. CLYDE L. MOOEf Patented Feb. 22, 1949 UNITED STATE s FATENT OFFICE 2,462,211 TRACTOR FIFTH-WHEEL SAFETY Look Clyde-L. Moore, Cleveland, Ohio ApplicatioriFebruary 24, 1947,- Serial No. "130,393 Claims. (01. 280-33455) This invention relates to couplers for articulatedvehiclessuchas'truck tractors and trailers, and relates particularly to safety type automatic fifth wheels:

GonduciVe to a better. understanding of the invention,- itshould be pointed out that quite frequently articulatedyehicles of the truck type become unhitched during; travel and; as a result, severe and costly accidents occur.- Frequently, during, cold weather, the oil and grease on the coupler hardens and prevents proper locking of the parts. Sometimes dirt and foreign particles find their way into the coupler mechanism and cause the operator or driver to believe that the device is properly locked; when actually it is not. Cases havebeenknown where pranksters or vandals have tampered with the conventional looks when such vehicles were left standing alone and unguarded; with theresult that when the driver returned and the vehicle took to the road, often at night. at high speed,- the sudden separation of thevehicle caused-a sudden death or injury.

The primary object of the invention, therefore, is to provide an automatically engaging locking device which safely connects the tractor and trailer together when the normally provided hitch or king-pin breaks or otherwise becomes disengaged or is accidentally left open,

Another object is tocontrol the degree of pressure on the piston lock pin or bolt in the event of failure of the snatch-hitch commonly used on fifth wheels.

A further object is to improveand simplify the means for bringing about adjustment of the relative positions of the safety lock in its connection with the fifthw-heel;

Still another object is to provide" a' device of the type stated that may be easily insta led and readily mounted on or attachedto -presently used conventional I couplers. I

A still further objectis to provide such device with a safety lock that" doesnot inhibit or. resist the'pivotal action of the coupler in the event the safety lock comes into operation on a turn of the road. i

A stll further object is to construct a fifth wheel safety device out of relativelya few but durable parts which will operate under careless operating conditions and which will not be effected by adverse weather conditions.

These and other objects of the'invention become apparent from a reading of the followingv description and claims,-to'get-her with the accompanying-'drawingain which like-parts are referred to. and indicated by like reference characters and wherein:

Figure l-is a side viewof an articulated vehicle ve'ntion;

fifth wheeler bottom part of the coupler taken substantially along the line and in the direction.

of the arrows 2-2 of the Figure 1; V,

Figure 3 is a side elevation of the fifth wheel shown in the Figure Figure 4 is an elevation of the front end of Figure 8 is an elevational view of another party of the device, taken along the line and in the direction of the arrows 8-8 of the Figure 5; v

Figure 9 is a horizontal or plan view of another 1 part of the device, taken along the line 9-9 of the Figure 6; i,

Figure 10 is an elevational view of another part of the device, taken along the line and in the direction of the arrows ill-i0 of the Figure 5; Figure 11 is a vertical cross-sectional viewof the element shown in the Figure 9;-

Figure 12 is a bottom view of the car-pin or landing plate taken substantially along the line and in the direction of the arrows I2l2 of the Figure 1; V Figure 13 is a side view of the pin plate shown in the Figure 12; V

Figure 14 is an exploded perspective view of the safety lock mechanism on the fifth wheel; and Figure 15 is a side elevation of the safety lock engaging the car-plate H! as in an emergency,

Referring to Figure 1- of the drawings there is shown a port on of an articu ated vehicle consisting of a tractor 20. a trailer 25, a coupler plate 30 and a fifth wheel 40.

The landing or coupler pl te 30 is more clearly shown on the Fi ures 12 and 13, and consists of a rather substantial metal sheet slightly larger than, the fifth wheel 40. It has a, conventional kin nin 3! depending therefrom and an arcuate slot 32 form d therein as shown. The metal of the ends of the slot are bent upward to form inclined portions 33 and wh ch slidab y engage the'herein after described bolt of the safety lock on the fifth wheel. This plate member 30 is firmly fastened to the bottom of the trailer at its forward end'by means of the screws or bolts 34. The king-pin- .H is flanged as shown in order to firmly engage the jaw of the snatch-hitch which will be' de; scribed in greater detail hereinafter.

Thefifth wheel, constituting the primary element of: this invention, is more clearly illustrated: in whole. or in partinthe drawings. with. the ex:-

ception of; Figures 12; and 13, The: fifthwheel,

consists ofa picibupplat 41., a snateh hitchfl a part of a safety lock 6|, a trigger device 7| and a manual lock or catch 9|. Each of these parts or members will be described in detail hereinafter and in the order stated.

The pick-up plate 4| is mounted on the rear of the tractor as shown and may be rigid or floating as desired. It consists of a stout disc of metal having a central hole or socket 42 therein for engaging the aforesaid king-pin 3|. Its rear portion 43 is tapered somewhat as shown. It has a rather large notch 44 which opens into the socket 42. The rear portion is inclined downward slightly to facilitate engagement with the coupler landing plate member 30.

The front part of the fifth-wheel pick-up plate 4| has a depending wall 45 on which the safety lock 6| is mounted. The wall also has a horizontal slot 46 for movably receiving the handle of the snatch-hitch 5|. It also has a vertical slot 41 which receives the lever arm of the trigger device 1|.

The snatch-hitch 5| is shaped somewhat as shown in the Figure 5. It is pivoted to the pickup plate 4| by the pin 52. Its rear end has a jaw 53 directly under the socket 42 which engages the king-pin 3| and the iianges thereof when the latter isinserted in the socket 42. This jaw 53 is so shaped and positioned that it automatically closes or engages the king-pin when the trailer is engaged with the tractor. The forward end of the hitch 5| has an arm and a handle 54 which moves in the horizontal slot 4B. The jaw 53 of the hitch is heavy and thick and provides a stout bearing for the king-pin. In the drawing, the character 5|a indicates the alternate position of the hitch.

The safety lock 6| is a bolt action device. It consists of a cylinder or receptacle 62 mounted vertically on the front of the fifth wheel. Inside the receptacle 62 there is a movable bar or plug of metal herein referred to as the bolt 63. The bottom of the bolt has a small link 64 attached thereto. A'durable and rather heavy expansion spring 65 is mounted in the bottom of the receptacle and tends to urge the bolt 63 upward or out of the receptacle. The receptacle has a vertical slot 61 which is aligned with the heretofore referred to slot 41. A small lid or cover 66 is provided for the receptacle 62 to prevent dust or other substance from entering into itand interfring with the proper action of the bolt 63.

Thetriggerdevice actuates the safety lock 6| when improper or unintentional separation of the vehicle takes place. It consists broadly of an L-shaped lever 12 and a slidable bar 16.

The L-shaped lever '12 is mounted vertically and so is pivoted on the horizontal pin '15. The horizontal arm 13 passes through and moves in the slots 41 and 67 and is connected to the link 64.

The slidable bar end 16 is mounted longitudi-. nally below the pick-up plate and slightly forward of the socket 42, and engages the vertical arm 14 of the L-shaped lever.

The rear portion of. the trigger bar 16 has an ascending portion 11 which abuts and is moved by theking-pin 3| as it passes through the notch into the socket 42.

Normally-when the tractor and trailer are separated, the ascending portion 1'! is under the central hole or socket 42, that is, at about where the center of the jaw 53 would be when the snatch-hitch '5|'is in its closed or locked position. 1 Whe'n the tractor and trailer are hitched as shown in the Figure 1, the ascending portion 17 is moved forward by theking-pin and flanges 4 thereof to a position slightly forward of the socket 42.

In order to properly coordinate the action of the bolt 63 with the action of the slidable bar 16, an adjustment means is attached to the lever arm 14 which directly engages the front portion of the slidable bar. This is necessary so that the projected bolt 63 will engage the arcuate slot 32 before the king-pin 3| is removed or otherwise displaced from the socket.

The adjusting means referred to is really an extension of the arm 14. It consists of a short arm 8| pivoted to the lever arm 14 at the pin 82. It has a finger portion which is engaged by and directly contacts the bar end 16. Below the finger portion 85 and above the pivot pin 82,

there is a bracket 83. This bracket 83 is attached 1 to the arm 14 and has two aligned parallel lugs 86. These lugs 86 are drilled and tapped and suitably provided with set screws 84. The set screws position the finger 85 on the lever 12 and thereby determines the position of the bar portion 16 for releasing the bolt 63 in an emergency. In the Figure 6, the characters 12a, 15 and 63a indicate the relative alternate positions of the lever 12, the bar 16 and the bolt 63.

It is desirable at times to be able to fix the bolt 53 and the lever 12 in the normal or unlocked emergency position. For this p p se, there is provided a manual catch 9| which slides acrossthe slots 41 and 61. This catch slides over the horizontal arm 13 of the L-shaped lever and this prevents the bolt 63 from being projected regardless of the position of the movable bar 16.

This manual catch 9| has a longitudinal'slot 92 therein, through which passes two shouldered bolts 93. The end 94 is movable to engage the lever arm 12. A small compression spring 95 tends to keep the catch in the free or open position so that thelever arm 12 may actuate the bolt 63 if necessary. The other end of the catch 9|, which is mounted on the depending wall 45 of the pick-up plate,- has a notch 95 therein for engaging the pin 91. construction is clearly shown in the Figure 8. The spring 99 retains the catch in its locked position.

When used, the fifth-wheel 4|], together with the snatch-hitch 5|, the trigger means 1|, and

the safety bolt or look 6| and their respective wherein, since it is not a part of this invention.

However, its design and application are well known in the art.

When connecting the tractor and trailer together for transport, the tractor 20 is slowly backed up so that the notch 44 and the central socket of the fifth-wheel engage the king-pin 3|. When the king-pin nears the center of the socket, two things occur almost simultaneously. First, the king-pin 3| strikes the upright portion 1! of the slidable bar and moves it forward. Sec

0nd, the king-pin strikes the inner side of the jaw 53 and causes the snatch-hitch 5| to move inward or toward the center and under the opening 42. The king-pin is thus automatically engaged. The standard'lock foundon most conventional fifth-wheels consists of a snatch-hitch similar to the one indicated herein as To release the standard lock, a lever like the one indicated at 54 is pulled outward while the tractor is slowly moving forward.

When the king-pin 3| is properly engaged and in the opening 42, the end ll of the trigger means is in the position shown in full lines in the Figure 6. The front end of the slidable bar 16 is forward and forces the upright arm M of the L-shaped lever to be in its vertical position. The arm 13 is thus made to assume its horizontal position and the bolt 63 is drawn downward or inward against the compression of the spring 65. The lid or cover 66 is automatically closed and the bolt 65 and the trigger H elements are as shown in the full lines of the Figure 6. When in this position, th stress and strain of the pivoted connection between the tractor and trailer are entirely centered at the king-pin H and the jaw 53.

In the event of an accident, for example if the jaw 53 should break or if the snatch-hitch pin 52 should shear off or loosen, the king-pin would immediately tend to move out of the central hole or socket 42. However, before it has a chance to move very far out of its normal central position, the L-shaped lever 14 will assume an inclined position somewhat as shown in the Figure 15 and by the broken lines of the Figure 6. When in this inclined position, the compression spring 65 will urge the bolt 63 to its upward or engaging position and, when in such engaging position, the projecting head of the bolt will fit into the arcuate slot 32 of the landing plate 30. Therefore, the stress of the connection between the two vehicles is transferred to the bolted and slotted landing plate from the normally engaged king-pin and jaw members. While thus engaged, in an emergency the vehicle may continue en route and until repairs to the major connection can be conveniently made. This emergency engagement of the bolt with the landing plate will prevent injury and damage ordinarily caused by a complete separation of the two moving vehicles.

, It has been further found from experience that most separation accidents of vehicles of this type occur when rounding corners or on sharply curved highways. This is probably due to the centrifugal force acting on the points of major connection, in addition to the normal longitudinal strain of the pulling action. Therefore, in order to provide for such situations, the engaging slot 32 of the landing plate 30' is made curved or arcuate as shown so that the bolt 63 may be engaged even though the two vehicles are on a curve or are otherwise maligned,

Having thus disclosed the invention in its preferred form, it should be understood that there may be other forms or modifications of the invention which might also come within the scope of the claims, as no limitations or restrictions are intended except those imposed thereon by the scope of the following claims.

I claim:

1. In an articulated vehicle, a safety coupler, comprising in combination, a fifth-wheel having a socket, a plate member having a king-pin engageable by the socket and an arcuate slot therein, a snatch-hitch mounted on the fifthwheel engageable with the king-pin, and a safetylook mounted on the fifth-wheel and including a trigger means capable of being actuated by the king-pin when the latter is unintentionally disengaged from the snatch-hitch and a bolt mechanism connected to the trigger means engageable by the arcuate slot when the said trigger means is actuated.

2. In an articulated vehicle, a safety coupler, comprising in combination, a fifth-wheel having a central socket and a vertical receptacle mounted on the tractor of the articulated vehicle, the said receptacle having a cover, a plate member having a king-pin engageable by the socket and an arcuate slot proximate to the receptacle mounted on the trailer of the said articulated vehicle, an automatically operating bolt device normally in the covered receptacle and capable of extending into the said arcuate slot, and a safety-lock mounted on the fifth-weel and having a trigger portion actuated by the king-pin capable of releasing the bolt for extension into the arcuate slot.

3. In an articulated vehicle, a safety coupler, comprising in combination, a fifth-wheel having a socket, a plate member having a king-pin engageable by the socket, a snatch-hitch mounted on the fifth-wheel engageable with the king-pin, a safety-lock mounted on the fifth-wheel and including a trigger means capable of being actuated by the king-pin when the latter is unintentionally disengaged from the snatch-hitch and a bolt mechanism connected to the trigger means engageable with the plate member when the said trigger means is actuated and a manually operable catch means mounted on the fifth-wheel retaining the said snatch-hitch and safety-lock in normally hitched and unlocked positions.

4. A fifth-wheel, comprising in combination, a pick-up plate having a central socket therein and a bolt device mounted thereon, an L-shaped lever vertically mounted below the pick-up plate and having the horizontal arm thereof connected to the said bolt and a slidable bar mounted below the pick-up plate proximate, to the central socket and movable by a coupler king-pin, the said slidable bar being linked to the vertical arm of the said lever.

5. A fifth-wheel, comprising in combination, a pick-up plate having a central socket therein and a bolt device mounted thereon, an L-shaped lever vertically mounted below the pick-up plate and having the horizontal arm thereof connected to the said bolt, 2. slidable bar mounted below the pick-up plate proximate to the central socket and movable by a coupler king-pin, the said slidable bar being linked to the vertical arm of the said lever and a manually operable catch means mounted on the pick-up plate proximate to the bolt and engageable with the horizontal arm of the said lever and capable of retaining the same in a predetermined position.

' CLYDE L. MOORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,043,342 Walker June 9, 1936 2,318,038 Winn May 4, 1943 2,400,738 Brown May 21, 1946 

